Prepare for removal of legacy-test from default targets

In preparation for removing junit classes from the Android API
the legacy-test target will be removed from the
TARGET_DEFAULT_JAVA_LIBRARIES. This change adds explicit
dependencies on junit and/or legacy-android-test to ensure that
modules will compile properly once it is removed.

Bug: 30188076
Test: make checkbuild
Merged-In: Ide9513b330a48982b907a3a663fec065edf683c2
Change-Id: Ib65f505d47fbd9bbd1145a04ff5f7a2aeb62345a